System and fitting for choke tube repair

ABSTRACT

A choke tube repair fitting having an elongated body tapered at one end to be driven into the stub of a broken choke tube, having a breakaway collar adapted to receive the driving force and to break away when a predetermined level is reached, and having a counterbore at its other end to receive the remainder of the choke tube is disclosed as an effective means for the repair of choke tubes on automobile engines. Drive fasteners with breakaway collars of the kind described are not limited to this particular repair; but have general utility.

United States Patent [191 Guhman Mar. 12, 1974 [5 SYSTEM AND FITTING FOR CHOKE TUBE 2,993,267 7/1961 Helwig 29/401 REPAIR [76] Inventor: Kenneth James Guhman, 7 Depot Primm'y Examiner wenden Bums Rd. South Grafton Mass 01560 Attorney, Agent, or FzrmJack Larsen [22] Filed: Mar. 20, 1972 57 ABSTRACT [21] Appl. No.1 236,370 1 A choke tube repair fitting having an elongated body tapered at one end to be driven into the stub of a bro- [52] U.S. Cl 123/119 F, 29/401 ken choke tube, having a breakaway Collar adapted to Cl. recei e the dri ing force and to rea a ay hen a [58] F'eld Search 29/401 predetermined level is reached, and having a counter- 123/198 F bore at its other end to receive the remainder of the 56 R f d choke tube is disclosed as an effective means for the 1 .eerences repair of choke tubes on automobile engines. Drive UNITED STATES PATENTS fasteners with break-away collars of the kind de- 2,608,389 8/1952 Boyce 123/119 F scribed are not limited to this particular repair; but 2,653,588 9/1953 Meinzinger et al 123/119 F have general utility. 2,746,438 5/1956 Hutchison 123/119 F 2,762,352 Else 123/119 F 6 Claims, 2 Drawing Figures PAIENTEiJm 2 mm FIG. I

FIG. 2

SYSTEM AND FITTING FOR CHOKE TUBE REPAIR BACKGROUND OF THE INVENTION Many passenger automobiles are equipped with a thermostatic device for the automatic control of the choke valve in the carburetor. The choke enriches the mixture by cutting down the air. When the engine is cold, choking is required. Automatic chokes are adapted to be responsive not only to the temperature of the carburetor and the ambient air; but also to the combustion chamber temperature. It is not convenient to measure the latter temperature directly, so exhaust manifold temperature is used as an approximation. The choke which is rotated by a bimetallic coil is made responsive to exhaust manifold temperature by drawing air through a so-called choke tube from the manifold where it is heated to the choke control coil and on into the intake manifold. In the exhaust manifold there is a heat exchanger that provides a passage for the air to pass through the manifold to be heated but must keep exhaust gases from leaking into the choke tube. The choke tube is rooted in this heat exchanger by the manufacturer by pressing into the heat exchanger or by some other operation which makes a secure inexpensive connection without a fitting. In consequence of the means of attachment and of the severe environmental conditions to which this junction is exposed, very often after some years of use, the choke tube breaks off right at the point where it enters the manifold. Sometimes the heat exchanger itself becomes-clogged or leaky. In either case, the replacement of the manifold represents an expense which is disproportionate to the value of the aged vehicle. A simple, inexpensive repair that will substantially, if not perfectly restore the operation of the automatic choke is to be preferred, and this invention relates to such a repair.

The so-called choke stove disclosed in U. S. Pat. No. 2,993,267 represents one such expedient. For some years Toke Products, Inc. of South Grafton, Massachusetts, has been making and selling a Model UX-4 Choke Stud" comprising basically a /2 inch steel bolt hollowed out byv a 5/16 inch counterbore. The stud is screwed into a hole drilled and tapped in the exhaust manifold, and a piece of inch O.D-. tubing fits loosely into the well provided by the counterbore to convey to the choke control air warmed by heat conducted through the wall of the stud. Drilling and tapping the cast iron manifold with so large a hole is a substantial undertaking in the restricted space often available around an engine. More recently this same company has supplied a smaller fitting designed for those cases wherein the original heat exchanger is still sound. This fitting, also of steel, has an elongated main body of hexagonal stock with a passage extending through it for the warm air. At one end it is formed into a metal-cutting screw thread formed as a tapered helix of relatively .long lead which may be screwed into theremanent of the broken-off choke tube, while the other end is adapted to accept a replacement tube for connection to the choke control. A wrench applied to the hexagonal body provided a convenient means for attachmenttoo convenient since excessive force is often applied, twisting the body off and leaving the hard screw portion partially plugging the stub of the choke tube.

It is therefore a primary object of the invention to provide a choke-tube repair fitting of more general application. It is a further object of the invention to provide a family of fittings and fasteners which are selflimiting in the installation force.

A feature by which the above objects are attained is the use of aluminum for the body of the fitting. Aluminum being a good conductor of heat, the fitting may serve as a heat exchanger. Moreover the aluminum fitting maybe driven into the manifold to make a gastight joint with low thermal resistance. 7

A further feature of the invention is the provision of a breakaway collar on the fitting so that the proper amount of driving force and no more is applied when fitting the part to the manifold.

. Other objects will be in part obvious and in part apprehended from the following specification in connection with the accompanying drawings of which:

FIG. 1 is a sectional view of the preferred embodiment of the invention with the tool for inserting it, and

FIG. 2 is a sectional view of an alternative embodiment proportioned to illustrate its function in situations where the heat-exchanger is defective.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1, the choke-tube repair fitting 10 is shown connected to the stub end 12 of a broken choke tube, which is held in the heat exchanger tube 14, which passes through the exhaust manifold 16.

The fitting 10 has a passage 18 extending longitudinally therethrough. A slightly tapered surface 20 is formed on the lower end proportioned to make a press fit with the inside diameter of the stub end 12. On the more popular American automobiles, this tube is 5/ l6ths of an inch nominal inside diameter Bundyweld copper-clad steel tubing.

The upper end of the fitting 10 has an outer cylindrical surface 22, and a counterbore 24 sized to fit the outer diameter of the choke tube.

Centrally the surface 22 is bounded at its lower end by a breakaway ring 30 formed integrally with the fitting and presenting an upper flange surface 32' which extends out radially from the surface 22 to present sufficient area to the hollow tool 40 to sustain the driving force as the tool is driven by a hammer to press the fitting into the stub tube 12. The ring 30 is proportioned so that it is sheared from the body of the fitting 10. For choke tube repair it is satisfactory, even preferable, that the sheared-off ring continues to encircle the fitting where it meets the manifold. To accommodate this, the body has a central portion 42 extending below the ring 30 with somewhat smaller diameter than the surface 22.

The ring may be notched to break into pieces if that is preferred in other uses. To insure that the ring break at the predetermined place and at the predetermined force, a groove 46 may be cut on the lower surface 48 of the ring (or on the upper face 32).

The tool 40 is made by slicing off sections of highbreakaway collar 60 at its head end which may be driven by the tool 40.

Alongside the heat exchanger tube 14, a hole 64 is drilled into the manifold. Typically 3/l6th inch in diameter, this hole is conveniently made with a small electric drill. Into this hole 64 a fitting is driven, the passage 18 having been plugged with an aluminum nail 66. As the tapered surface 20 is forced into the hole 64, the nail 66 is more firmly gripped so that the fitting is gas tight. The breakaway-ring 30 is shown broken away, leaving broken surfaces 70, 72 on the ring and fitting respectively. The choke tube 80 cut off on a slant is inserted in the counterbore 24 to form a leaky joint. Insulating fiberglass braid 82 is then brought down to cover the fitting. The fitting, made of aluminum, efficiently draws heat from the hot exhaust gases. Air drawn through the braid 82, leaks through the space 84between the counterbore and the tube 80, passes around the end of the tube, drawing heat from the fitting and the nail 66, and continues upward through the tube 80 to the choke control and the intake manifold.

The heat exchanger so formed is not likely exactly to match the manufacturers specifications, generally being a little slow to react; but the minor loss of fuel efficiency is a small cost to pay when compared to the replacement of a manifold.

lt is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent l. A reconstructed choke control'system for a gasoline engine of the kind which was originally equipped with a heat-sensitive automatic choke to which air was delivered from a heat exchanger tube in the exhaust manifold through an original choke tube to a choke control coil whereby the choke opened automatically as the engine heated up, and wherein said heat exchanger had been rendered ineffective by the development of a leak in said heat exchanger tube which permitted exhaust gases to enter said choke tube, said reconstructed system comprising,

I a. a plug for blocking said heat exchanger tube,

b. a modified choke tube, adapted to connect at one end to said choke and c. a fitting,

d. said fitting having at its upper end a counterbore to receive the other end of said modified choke tube, and at its lower end a tapered surface adapted to be driven into a hole drilled to receive it in said manifold.

2. A system as defined by claim 1(e) wherein said fitting has an outer cylindrical surface bounded at its lower end by a breakaway ring formed integrally and presenting an upper flange surface which extends out radially to present sufficient area to hollow tool, to sustain the driving force as said tool is driven by a hammer to press said fitting into said hole, said ring being so proportioned that it shears off when said fitting is .seated to a predetermined degree, thereby protecting said fitting from excessive driving force.

3. A system as defined by claim l e. said modified choke tube having its other end cut off at a slant so as not to seat tightly in said counterbore.

4. A system as defined by claim 1 e. said modified choke tube having its other end modified to form a leaky joint with said fitting.

5. A system as defined by claim 1(e) wherein said plug comprises a fastener having a tapered portion at one end adapted to be driven into said exhanger tube, and around the other end a breakaway ring proportioned to limit the force with which said plug is seated.

6. A reconstructed choke control system for a gasoline engine which was originally equipped with a heatsensitive automatic choke to which air was delivered from a heat exchanger tube in the exhaust manifold through an original choke tube to a choke control bimetallic coil whereby the choke was opened automatically as the engine heated up, said reconstructed system comprising,

a. a modified choke tube, adapted to connect at one end to said choke, and

b. an aluminum fitting,

c. said fitting having at its upper end a counterbore to receive the other end of said modified choke tube, at its lower end a taper adapted to effect a gas-tight pressed connection to said manifold, and a breakaway ring formed integrally and presenting an upper flange surface which extends out radially to oresent sufficient area to a hollow tool to sustain the driving force required to effect said pressed connection, yet also proportioned so that it shears off when unsafe excessive force is applied.

l l =l 

1. A reconstructed choke control system for a gasoline engine of the kind which was originally equipped with a heat-sensitive automatic choke to which air was delivered from a heat exchanger tube in the exhaust manifold through an original choke tube to a choke control coil whereby the choke opened automatically as the engine heated up, and wherein said heat exchanger had been rendered ineffective by the development of a leak in said heat exchanger tube which permitted exhaust gases to enter said choke tube, said reconstructed system comprising, a. a plug for blocking said heat exchanger tube, b. a modified choke tube, adapted to connect at one end to said choke and c. a fitting, d. said fitting having at its upper end a counterbore to receive the other end of said modified choke tube, and at its lower end a tapered surface adapted to be driven into a hole drilled to receive it in said manifold.
 2. A system as defined by claim 1(e) wherein said fitting has an outer cylindrical surface bounded at its lower end by a breakaway ring formed integrally and presenting an upper flange surface which extends out radially to present sufficient area to hollow tool, to sustain the driving force as said tool is driven by a hammer to press said fitting into said hole, said ring being so proportioned that it shears off when said fitting is seated to a predetermined degree, thereby protecting said fitting from excessive driving force.
 3. A system as defined by claim 1 e. said modified choke tube having its other end cut off at a slant so as not to seat tightly in said counterbore.
 4. A system as defined by claim 1 e. said modified choke tube having its other end modified to form a leaky joint with said fitting.
 5. A system as defined by claim 1(e) wherein said plug comprises a fastener having a tapered portion at one end adapted to be driven into said exhanger tube, and around the other end a breakaway ring proportioned to limit the force with which said plug is seated.
 6. A reconstructed choke control system for a gasoline engine which was originally equipped with a heat-sensitive automatic choke to which air was delivered from a heat exchanger tube in the exhaust manifold through an original choke tube to a choke control bimetallic coil whereby the choke was opened automatically as the enGine heated up, said reconstructed system comprising, a. a modified choke tube, adapted to connect at one end to said choke, and b. an aluminum fitting, c. said fitting having at its upper end a counterbore to receive the other end of said modified choke tube, at its lower end a taper adapted to effect a gas-tight pressed connection to said manifold, and a breakaway ring formed integrally and presenting an upper flange surface which extends out radially to oresent sufficient area to a hollow tool to sustain the driving force required to effect said pressed connection, yet also proportioned so that it shears off when unsafe excessive force is applied. 